Only eight months after giving birth, Hilary Duff is back in her skinny jeans."Yaaaa bitches! Gabe johns your kickin my ass and its paying off! Skinny jeans! LETS GO!" Duff tweeted, along with a photo of her size 26 jeans.Check out celebrities' dramatic weight lossDuff has been hard at work since welcoming son Luca in March. In October, the actress teamed up with personal trainer Johns to help get a rockin' post-baby bod."Hilary and Gabe have been doing everything from boxing to two-a-day workouts incorporating wind springs and jump roping in an effort to finally shed the baby weight," a rep for Johns told Us Weekly. "Hilary's been steadily dropping pounds each week."